Polycarbonate compositions containing inorganic materials are known. The inorganic materials are used in these compositions for example as reinforcing agents in order to increase the rigidity and tensile strength, to increase the dimensional stability under temperature fluctuations, to improve the surface properties or—in flame-resistant materials—also as flame-proofing synergists. Depending on the area of application and intended use inorganic materials may typically be used in concentrations of 0.5 to 30 wt. %. Both mineral and artificially obtained materials are used.
WO 98/51737 discloses polycarbonate/ABS compositions (PC/ABS) that contain 1 to 15 wt. % of a mineral filler such as talcum or wollastonite. The use of the types of fillers and concentrations described in this document point to an iron content of significantly more than 100 ppm in the composition.
The PC/ABS compositions disclosed in U.S. Pat. No. 5,091,461 contain talcum and uncalcined clay materials as inorganic fillers. The types of talcum used are characterized by a relatively high iron content.
The polycarbonate compositions of U.S. Pat. No. 5,162,419 and EP-A 0 758 003 give no indications of the iron content of the contained inorganic fillers. U.S. Pat. No. 5,961,915 discloses amorphous thermoplastic compositions that have been rendered flame-resistant with phosphoric acid esters and that contain glass chips or mica as inorganic filler. Such fillers or reinforcing agents often have relatively high iron concentrations.
JP-A 11/199768 discloses flame-resistant PC/ABS compositions containing talcum and phosphoric acid esters, in which different types of talcum are employed. This document gives no indication of the effect of the different types of talcum on the property spectrum of the blends produced therewith.
The addition of inorganic materials to PC/ABS blends leads in all cases, as expected, to a significant deterioration in the toughness of the molded article produced from the composition. Often the toughness achieved on adding inorganic materials is accordingly either insufficient for special applications or the amount of inorganic material employed is too small in order to be able to realise to a satisfactory degree the property advantages envisaged by its use.
It is therefore desirable to be able to provide polycarbonate compositions to which inorganic materials such as reinforcing agents having an anisotropic particle geometry have been added in a known manner in order to improve at least one material property, and which moreover are characterized by an improved toughness and/or low temperature toughness behavior compared to the prior art.